ABSTRACT
The purpose of using water with cement is to cause hydration of the cement. Water in excess of that required for hydration acts as a lubricant between coarse and fine aggregates and produces a workable and economical concrete. The effects of impurities in water are mainly expressed in terms of setting time of Portland cement. Water fit for making concrete can be used for curing. Sea water may be recommended for concrete without reinforcement. Algae present in mixing water or on the surface of aggregate either reduces bond by combining with the cement or reduces strength by entraining a large amount of air in the concrete. When industrial waste water is used as mixing water in concrete, the reduction in compressive strength is generally less than about 10 per cent. When aggregates are washed with water containing impurities, they get coated with layers of silt, salts and organic matters.
